This result should have offered West Ham United respite, a win that ended the team's recent Premier League slump and propelled them back towards the deceptive security of mid-table, and yet the final whistle on Wednesday night still drew a chorus of boos from the home fans. Even in victory, there is dissatisfaction. Sam Allardyce cupped his hand to his ear at the sound, his smile betraying incredulity at the reaction.

The victory against 10 men came through a penalty that Hull rightly disputed and which resulted in their goalkeeper, Allan McGregor, being sent off and a timely own goal from the Hull defender James Chester just as fear was starting to grip the home players yet again.

Allardyce, who had just endured his first three-game losing run since arriving at Upton Park, argued it was a time for pragmatism. This victory took West Ham nine points clear of 18th-placed Sunderland, whom they visit on Monday, yet such a chasm seems remarkable given the way this team spluttered as they did for long periods here, their football lacking guile and purpose even if the manager said they were "absolutely magnificent".

The crowd railed at every sideways or backward pass, perplexed as to why opponents who had been reduced in number midway through the first half could not be overwhelmed. "I couldn't quite believe the booing," said Allardyce. "I started in the game at 16, got into the first-team at 18 and I'm 59 now, and I have never been in a place where we have won and got booed. I can't understand it. Yes, we wanted to play better and score more goals against 10 men. Everyone expects you to. But look what we did with 10 winning against Cardiff and Swansea. You can't assume you'll win 3-0. I'd urge the fans to stay behind their team because it'll affect the players otherwise. It must be the frustration."

Hull, too, had reason to be exasperated. They disputed McGregor's dismissal, arguing West Ham had committed an offence in the build-up to the penalty award and pointing to a covering defender. Mark Noble had darted through the centre and his pass ricocheted off Chester and Tom Huddlestone before the ball reached the marauding Mohamed Diamé in front of goal, the Senegalese controlling it with his arm as he careered forward and poked his shot over the advancing goalkeeper.

While the attempt was scrambled from the goalline, the referee, Mike Dean, blew for the penalty once he had noticed that both McGregor and Diamé were lying on the turf. "First of all it's a blatant handball," said Steve Bruce. "[Dean] told me at half-time he'd made the decision himself. Nobody else. When you look at him, though, he doesn't make the decision at all. He turns back 10 seconds later and sees the players lying in a heap, and then awards the penalty.

"So if he's reacting retrospectively because someone is injured, how can he be sure about it? And we must have had someone level because we've cleared the ball off the line, so was he really denying a goalscoring opportunity?"

McGregor was dismissed as he groggily got to his feet and he spent the night in hospital having suffered an injury that may well end his season. "He's in a bad way, kidney damage," said Bruce. "A specialist is on his way to see him, a contusion on his kidney. We're hoping it's not ruptured."

That was sobering. Noble scored the penalty, though West Ham showed little fluency thereafter, with Hull thrusting themselves back into the contest. Maynor Figueroa had threatened an equaliser with one powerful effort from distance which was turned aside by Adrián, before Huddlestone's free-kick deflected off Nikica Jelavic and beyond the goalkeeper to level.

For a while the mutinous crowd teetered on open revolt, only for Hull to surrender the initiative. Guy Demel was free to cut inside on to his left foot and send over an in-swinging centre which bypassed Kevin Nolan on the edge of the six-yard but drew an instinctive swing of the leg from Chester, the ball cannoning off the Hull centre-half's knee past Steve Harper, sent on for Alex Bruce after McGregor's departure.

The defeat was harsh on Bruce's rugged side, who rallied late on even with weary limbs and Adrián had to save well late on to deny Huddlestone a second equaliser for Hull. "I thought we were absolutely terrific," said Bruce. They have still to drop below 13th place since September and, like West Ham, will feel tantalisingly close to safety.